Questions tagged [diaphragm]

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5answers
399 views

EOS 250D the aperture changing only when picture is taken

I have yongnuo 50mm f1.8 lens In Av Mode When I m changing the fstop the diaphragm blades remains fully open and depth of field doesn't change I have looked to user Guide and find that I can assign ...
-1
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3answers
90 views

Real light increments using aperture scale in fractional stops

In the case of using f-number with full stops, the +1EV step means 2*light because the Area (A = πr^2) in the diaphragm is doubled (i.e. radius*√2). However, I don't know why in fractional stops such ...
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votes
3answers
104 views

What techniques do higher-end lenses use to reduce astigmatism at high apertures?

I own a few lenses with a maximum aperture of f/2.8. For this question, I'll focus on two specifically: A Rokinon 14mm f/2.8, which retails around the $500 CAD mark; and A Sigma 24-70 f/2.8, which ...
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votes
1answer
106 views

How is the diameter of a non-circular (effective) aperture actually measured?

An f-number is determined as the ratio of the focal length to the diameter of the entrance pupil. But the actual aperture diaphragm is usually not a perfect circle. Its shape is determined by the ...
0
votes
1answer
154 views

Canon 24-105mm aperture diaphragm screw size

I need to mount a Canon 24-105mm aperture diaphragm unit to something, but I don't have any screws for it. In the lens itself, it is attached to some sort of mount via 3 screws that screw into the ...
0
votes
3answers
79 views

Is there a difference in image when using a two different combinations of exposure time and diaphragm? [duplicate]

My camera, aimed at a motionless object, is mounted on a tripod. Do I get a different image by changing exposure time and the diaphragm in such a way that the total amount of light coming in stays the ...
1
vote
2answers
122 views

Is there a datasheet for the Canon 24-105mm diaphragm unit?

Does anyone know if a datasheet is available for the Canon 24-105mm diaphragm unit? I'm wondering if there's a way to use an Arduino or suchlike to control the diaphragm via the flex cable, but I can'...
3
votes
1answer
4k views

What is an electromagnetic diaphragm?

What is an electromagnetic diaphragm, how it works, and how is it different with regular diaphragms? A specialized electromagnetic diaphragm mechanism operates in precise sync with the camera's ...